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Antibiotics Q&As

Published by Bupa's health information team, June 2009.

Answers to questions about antibiotics

This section contains answers to common questions about this topic. Questions have been suggested by health professionals, website feedback and requests via email.

 

How does my doctor chose the right antibiotic to treat my infection?

Your doctor will check your symptoms, consider which bacteria could be causing your infection and then identify the best antibiotic for you. This decision will be based upon your medical history, including factors such as whether you have any allergies to certain antibiotics, are pregnant, and the severity of your infection. You may receive a 'broad-spectrum' or 'narrow-spectrum' antibiotic. A broad-spectrum antibiotic kills a wide range of bacteria and a narrow-spectrum antibiotic is only effective against specific types of bacteria.

Explanation

Before choosing an antibiotic, your doctor will ask you about your symptoms, and if relevant, may ask if you have travelled abroad recently or if you have any problems with your immune system. He or she will consider which bacteria are likely to be causing your infection. This will enable your doctor to suggest the use of one or more antibiotics.

If your doctor is unsure which bacteria are causing your infection, he or she may prescribe a broad-spectrum antibiotic. This type of antibiotic kills a wide range of bacteria. If you have a potentially serious infection, you will usually be given a broad-spectrum antibiotic so that there is no delay in your treatment. Any delay in treatment could lead to your illness becoming rapidly worse. Broad-spectrum antibiotics aren't always the best solution, as their use can cause bacteria to become resistant. Resistance can start when bacteria causing an infection aren't completely killed off by the antibiotic used. Some bacteria survive because they have an inherited mutation (change) that makes them more resistant to a certain antibiotic.

If this happens, your doctor may need to prescribe a different antibiotic.

If your doctor is fairly sure which bacteria or family of bacteria is causing your infection, he or she may prescribe a narrow-spectrum antibiotic. This type of antibiotic is only effective against specific types of bacteria.

Your doctor may ask you to provide samples, such as a sample of faeces (also called a stool sample) if you're being sick or have diarrhoea. These samples will be tested in a laboratory to see which bacteria are causing your infection, allowing your doctor to prescribe the best antibiotic.

The final choice of which antibiotic you will be given will also depend on your medical history. This includes any allergies to specific antibiotics, the health of your kidneys and liver, the severity of your infection, your chance of getting another infection, and whether you're pregnant or breastfeeding. You may be allergic to penicillin antibiotics - these can cause serious reactions (called anaphylaxis) in some people.

The duration, dosage, and route of administration of your course of antibiotics will depend on the location, type and severity of your infection. Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Further information

Sources

  • Longmore M, Wilkinson IB, Rajagopalan S. Oxford Handbook of Clinical Medicine. 6th ed. Oxford: Oxford University Press, 2004:543-548
  • Warrell DA, Cox TM, Firth JD. Oxford Textbook of Medicine. 4th ed. Vol 1. Oxford: Oxford University Press, 2005:296-297
  • Joint Formulary Committee, British National Formulary. 54th ed. London: British Medical Association and Royal Pharmaceutical Society of Great Britain, 2007: 274-275; 281
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Why won't my GP give me antibiotics for my flu?

Antibiotics are only effective against infections caused by bacteria. As flu is caused by flu viruses, antibiotics shouldn't be used for this type of infection. Antibiotics may sometimes be used if you develop a secondary bacterial infection while you have flu or are recovering from it. Secondary infections can develop if your body has been weakened by fighting a flu infection and isn't strong enough to fight off other infections.

Explanation

Antibiotics are used to help your immune system fight bacterial infections but aren't effective in treating viral infections like flu which is caused by flu viruses. Flu is caused by three main types of virus, known as influenza A, B and C.

Your body may be weakened after fighting a flu infection, making it more likely that you will develop a secondary infection caused by bacteria. Your body may find it difficult to fight off this secondary infection and your GP may have to prescribe antibiotics. Secondary infections can affect your chest, ears, nose and/or throat. If you're elderly or have existing conditions such as diabetes, heart disease, or problems with your breathing, you might develop a serious secondary infection such as pneumonia. If you have flu, it can take up to two weeks to clear up. However, contact your GP if you're concerned about any of your symptoms, particularly if they persist.

Having a dose of flu vaccine each year can help prevent you getting flu. Contact your GP to see if you're eligible.

If you're usually fit and healthy, you can treat the symptoms of flu at home using remedies commonly available from pharmacies. You should stay at home and in bed for as long as the symptoms last, which is usually two or three days after the symptoms are at their worst. You should drink plenty of fluids and get plenty of rest.

Medicines that fight the flu virus are called antivirals. They don't cure the virus but may reduce the severity of symptoms and how long they last. The antivirals zanamivir and oseltamivir may be prescribed during a flu outbreak. They work by stopping the virus from multiplying in your body. Always ask your GP for advice and read the patient information leaflet that comes with your medicine.

Further information

Sources

  • Simon C, Everitt H, Kendrick T. Oxford Handbook of General Practice. 2nd ed. Oxford: Oxford University Press, 2007:490-491
  • Influenza. Clinical Knowledge Summaries. http://cks.library.nhs.uk, accessed 6 August 2008
  • Joint Formulary Committee, British National Formulary. 54th ed. London: British Medical Association and Royal Pharmaceutical Society of Great Britain, 2007: 284-286; 338
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If I feel better after a few days, can I stop taking my antibiotics?

You should always finish your course of antibiotics even if you feel better after a few days. Although you may feel better, bacteria causing your infection may still be present in your body and you will need to finish your course of antibiotics to stop them from causing another infection. Stopping antibiotics too early may also increase the risk of antibiotic resistance, where bacteria stop being killed by the antibiotic. Resistance can lead to further, and possibly more serious, infections.

Explanation

You will need to continue taking the antibiotics for the full course of treatment to clear your infection completely, as directed by your doctor. You should do this even if you begin to feel better after a few days. If you stop taking your antibiotics too soon, then your symptoms may return. Serious complications, such as heart problems, can develop later on with some bacterial infections if they aren't completely cleared up.

Finishing your course of antibiotics will also reduce the chance of antibiotic resistance. If the bacteria causing your infection aren't completely killed off, they can change in a way that reduces or removes the effectiveness of antibiotics against them. Some bacteria survive because they have an inherited mutation (change) - this allows them to survive and multiply and can cause a longer illness. If the bacteria causing the infection you're being treated for become resistant, your doctor will need to prescribe a different antibiotic which is effective against these resistant bacteria.

Antibiotics are typically given for a period of seven to 10 days and you will usually need to take them at regular intervals throughout the day. It's very important that you take your antibiotics as prescribed by your doctor and follow the directions on the medicine label. Your antibiotics may also have special instructions to take them before, after, or during meals. This will ensure that you have the correct amount of medicine in your body to kill off the bacteria causing your infection.

If you miss a dose of antibiotic, take it as soon as possible. Then return to your usual dosing schedule. Don't double up on doses. If your antibiotics make you feel ill or you want to stop taking them for some reason, contact your doctor as soon as possible. Always ask your doctor for advice and read the patient information leaflet that comes with your medicine.

Further information

Sources

  • Longmore M, Wilkinson IB, Rajagopalan S. Oxford Handbook of Clinical Medicine. 6th ed. Oxford: Oxford University Press, 2004:152-153
  • Joint Formulary Committee, British National Formulary. 54th ed. London: British Medical Association and Royal Pharmaceutical Society of Great Britain, 2007: 274-275
  • Warrell DA, Cox TM, Firth JD. Oxford Textbook of Medicine. 4th ed. Oxford: Oxford University Press, 2005:296-297
  • Taking antibiotics. British Lung Foundation. www.lunguk.org, accessed 15 August 2008
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This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: June 2009

Antibiotics factsheet

 

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